Question

以下代码在哪里出错？

addNode()函数未运行，traverse()函数也未运行。

未显示最后的数据。

#include <stdio.h>
#include <stdlib.h>

struct isimler{
    char isim[10];
    struct isimler *next;
};

typedef struct isimler node;
node *head;

void createList(){
    int k, n;
    node *po;
    printf("Eleman Sayisi: ");  scanf("%d", &n);

    for(k = 0; k<n; k++){
        if(k == 0){
            head = (node *) malloc(sizeof(node));
            po = head;
        }else{
            po->next = (node *) malloc(sizeof(node));
            po = po->next;
        }
        printf("Isim Girin: "); scanf("%s",po->isim);
    }
    po->next = NULL;
}

void addNode(){
    node *po, *newNode;
    po = head;

    while(po != NULL){
        po = po->next;
    }

    po = (node *) malloc(sizeof(node));
    printf("Isim Girin: "); scanf("%s", po->isim);
    po->next = NULL;
}

void traverseList(){
    node *po;
    int i=0;
    po = head;

    while(po != NULL){
        printf("%d.\t%s\n",i,po->isim);
        po = po->next;
        i++;
    }
}

int main(){
    createList();
    traverseList();
    addNode();
    traverseList();

    return 1903;
}

Answer 1

您当前的addNode()方法会创建一个新节点，但不会将其添加到您的链接列表中。

您需要修改addNode()方法，如下所示：

void addNode(){
    node *po, *newNode;
    po = head;

    while(po->next != NULL) { // change this so you don't lose the end of the list
        po = po->next;        // po is now pointing to the last node in the list
    }

    newNode = (node *) malloc(sizeof(node)); // change this to newNode
    printf("Isim Girin: "); scanf("%s", newNode->isim);
    po->next = newNode; // add the new node here, don't set it to NULL
    newNode->next = NULL; 
}

Answer 2

您可以查看此代码并了解您遇到问题的确切位置

#include<stdio.h>
    #include<stdlib.h>
    #include<stdbool.h>

    struct test_struct
    {
        int val;
        struct test_struct *next;
    };

    struct test_struct *head = NULL;
    struct test_struct *curr = NULL;

    struct test_struct* create_list(int val)
    {
        printf("\n creating list with headnode as [%d]\n",val);
        struct test_struct *ptr = (struct test_struct*)malloc(sizeof(struct test_struct));
        if(NULL == ptr)
        {
            printf("\n Node creation failed \n");
            return NULL;
        }
        ptr->val = val;
        ptr->next = NULL;

        head = curr = ptr;
        return ptr;
    }

    struct test_struct* add_to_list(int val, bool add_to_end)
    {
        if(NULL == head)
        {
            return (create_list(val));
        }

        if(add_to_end)
            printf("\n Adding node to end of list with value [%d]\n",val);
        else
            printf("\n Adding node to beginning of list with value [%d]\n",val);

        struct test_struct *ptr = (struct test_struct*)malloc(sizeof(struct test_struct));
        if(NULL == ptr)
        {
            printf("\n Node creation failed \n");
            return NULL;
        }
        ptr->val = val;
        ptr->next = NULL;

        if(add_to_end)
        {
            curr->next = ptr;
            curr = ptr;
        }
        else
        {
            ptr->next = head;
            head = ptr;
        }
        return ptr;
    }

    struct test_struct* search_in_list(int val, struct test_struct **prev)
    {
        struct test_struct *ptr = head;
        struct test_struct *tmp = NULL;
        bool found = false;

        printf("\n Searching the list for value [%d] \n",val);

        while(ptr != NULL)
        {
            if(ptr->val == val)
            {
                found = true;
                break;
            }
            else
            {
                tmp = ptr;
                ptr = ptr->next;
            }
        }

        if(true == found)
        {
            if(prev)
                *prev = tmp;
            return ptr;
        }
        else
        {
            return NULL;
        }
    }

    int delete_from_list(int val)
    {
        struct test_struct *prev = NULL;
        struct test_struct *del = NULL;

        printf("\n Deleting value [%d] from list\n",val);

        del = search_in_list(val,&prev);
        if(del == NULL)
        {
            return -1;
        }
        else
        {
            if(prev != NULL)
                prev->next = del->next;

            if(del == curr)
            {
                curr = prev;
            }
            else if(del == head)
            {
                head = del->next;
            }
        }

        free(del);
        del = NULL;

        return 0;
    }

    void print_list(void)
    {
        struct test_struct *ptr = head;

        printf("\n -------Printing list Start------- \n");
        while(ptr != NULL)
        {
            printf("\n [%d] \n",ptr->val);
            ptr = ptr->next;
        }
        printf("\n -------Printing list End------- \n");

        return;
    }

    int main(void)
    {
        int i = 0, ret = 0;
        struct test_struct *ptr = NULL;

        print_list();

        for(i = 5; i<10; i++)
            add_to_list(i,true);

        print_list();

        for(i = 4; i>0; i--)
            add_to_list(i,false);

        print_list();

        for(i = 1; i<10; i += 4)
        {
            ptr = search_in_list(i, NULL);
            if(NULL == ptr)
            {
                printf("\n Search [val = %d] failed, no such element found\n",i);
            }
            else
            {
                printf("\n Search passed [val = %d]\n",ptr->val);
            }

            print_list();

            ret = delete_from_list(i);
            if(ret != 0)
            {
                printf("\n delete [val = %d] failed, no such element found\n",i);
            }
            else
            {
                printf("\n delete [val = %d]  passed \n",i);
            }

            print_list();
        }

        return 0;
    }

C中的链接列表add（）方法

2 个答案: